Collision Problem: Find Height & Heat Released

AI Thread Summary
A ball of mass 0.1 kg is free falling from a height of 1 m and has a coefficient of restitution (k) of 0.5. The height the ball will reach after the collision (h2) is determined using the equation h2 = k^2 * h1, resulting in h2 = 0.25 m. The calculations involve using energy conservation principles, specifically mgh for potential energy and (1/2)mv^2 for kinetic energy. The discussion highlights the importance of showing intermediate steps to identify errors in calculations. The final conclusion confirms that the correct height after the hit is indeed 0.25 m.
Xsnac
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Homework Statement


a ball of mass 0.1 kg, is free falling from the height (h1) of 1 m. hits the ground with a k = 0.5.
##k=\frac{v_2}{v_1}##
A)Height that the ball will reach after the hit.
B)The heat quantity released by collision

Homework Equations


I think ##mgh## and ## \frac{mv^2} {2} ##

The Attempt at a Solution


I found ##h_2## = 0,1 m , is this correct? .
divided the process in 2 steps :
##mgh_1= \frac {mv^2_1}{2}## and found ##v_1=\sqrt{2gh_1}##
and then did the same for the other 2 parts of the "movie"
##mgh_2= \frac {mv^2_2}{2}## and found ##h_2=\frac{v_2^2}{2g} ##
then I just replaced ##v_2## and calculated ##h_2##
 
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Xsnac said:
k=v2v1
I guess that means k=v2/v1.

0.1m is not correct. What did you get as intermediate results?

By the way: decimal point instead of comma in English.
 
mfb said:
I guess that means k=v2/v1.

0.1m is not correct. What did you get as intermediate results?

By the way: decimal point instead of comma in English.
well i found ## h_2 = \frac {k \sqrt{2gh_1}} {2g} ##
 
That equation is wrong (it has wrong units, it cannot work), but if you don't show your individual steps it is impossible to tell what exactly went wrong.
 
mfb said:
That equation is wrong (it has wrong units, it cannot work), but if you don't show your individual steps it is impossible to tell what exactly went wrong.
Ok let's see. after the 4 equations I posted on the first thread I found out ##h_2## with the following steps :
## \frac{mv^2_2}{2}=mgh_2## => ##h_2=\frac{v^2_2}{2g} ## , then I replace ##v^2_2## with ## (kv_1)^2## ok I found the error i think ? ##h_2=k^2h_1## ?? should it be 0,25 ?
 
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Xsnac said:
Ok let's see. after the 4 equations I posted on the first thread I found out ##h_2## with the following steps :
## \frac{mv^2_2}{2}=mgh_2## => ##h_2=\frac{v^2_2}{2g} ## , then I replace ##v^2_2## with ## (kv_1)^2## ok I found the error i think ? ##h_2=k^2h_1## ?? should it be 0,25 ?
Yes.
 
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